Heat exchangers are applied in many fields in order to transfer heat from a medium with relatively high temperature to a medium with relatively low temperature. Heat exchangers can be intended to cool relatively hot media. Heat exchangers can on the other hand also be intended to heat a relatively cold medium. This is for instance the case when heat exchangers are applied in central heating systems (CHs) or tap water systems. Water is heated in such systems by being brought into heat-exchanging contact with flue gases of a burner.
Conflicting requirements are often set for heat exchangers, and particularly heat exchangers for CH installations and tap water systems. The media thus have to be able to flow through the channels properly, i.e. with low pressure losses, and be brought into intensive contact with each other. At the same time a heat exchanger must be of relatively simple construction and capable of production at low cost and in large series. It must also be possible to clean and service heat exchangers in simple manner.
U.S. Pat. No. 1,966,133 discloses a heat exchanger comprising two castings. The castings are provided with a peripheral flange with openings, whereby they can be clamped against each other with bolts. Baffle plates likewise provided with a peripheral flange are clamped between the castings, whereby the heat exchanger can be disassembled, for instance for the purpose of cleaning operations or replacement of parts.
DE-C1-195 46 190 relates to a heat exchanger provided with a double plate-shaped pipe of a rectangular cross-section. Combustion gases flow from a combustion chamber in opposite directions along a water flow for heating. The outer channels transport the hot combustion gases which heat the water in the inner channel lying therebetween.